MLB.com's Todd Zolecki said the Phillies are "not terribly optimistic" about Lee recovering from the injury, but that the 36-year-old will try throwing through it.
Lee received a second opinion on his elbow from Dr. James Andrews after experiencing discomfort after throwing two innings in his spring debut last week.
If he cannot continue pitching through the injury, Lee would need surgery requiring a six-to-eight month recovery period, according to Zolecki. On Monday, Lee told ESPN that if he needs surgery, his season would be done and possibly his career.
Lee was limited by a strained flexor tendon in his elbow last season, pitching in only 13 games. He went 4-5 with a 3.65 ERA and 72 strikeouts in 81.1 innings.
Lee is due to make $25 million this season. He has a $27.5 million team option for 2016 and a $12.5 million buyout.
- Molly Geary
GALLERY: CLASSIC PHOTOS OF CLIFF LEE